In textile machines which process yarn, it is often necessary to provide a mechanism for taking-up of a predetermined length of yarn and for supplying of this yarn to the textile machine for various purposes. This is particularly true in the case of two-for-one twister textile yarn processing machines utilizing pneumatic or other types of automatic threading mechanisms for threading-up the spindle assemblies thereof upon starting-up of the spindle assembly or following breakage of the yarn during yarn processing. Such two-for-one twister textile yarn processing machines with pneumatic threading mechanisms for threading-up the spindle assemblies are disclosed in U.S. Pat. No. 3,731,478, issued May 8, 1973, and U.S. Pat. No. 3,975,873, issued Aug. 24, 1976, both of which are assigned to the assignee of the present invention.
As may be seen in each of these U.S. Patents, in order to accomplish suitable pneumatic threading-up of the spindle assemblies of these machines, the yarn must be pulled from the supply package of yarn and supplied to the entry of the yarn passageway through the spindle assembly in a substantially tension-free condition so that the suction and positive air stream created through the yarn passageway in the spindle assembly by the pneumatic threading mechanisms can effectively thread the yarn therethrough. Often, problems have existed with respect to removing the yarn from the supply package and supplying it to the passageway in the spindle assembly for automatic pneumatic threading in a substantially tension-free condition. Accordingly, there is a need, particularly in these types of twisting machines, for a yarn take-up and supply mechanism which can take-up a given length of yarn and supply this yarn to the textile machine in a substantially tension-free condition.
Heretofore, yarn take-up and supply mechanisms, also called yarn regulating devices, have been typically used in weaving and knitting machines and were instrumental in insuring the slip-free positive supply of fixed lengths of yarn at high running speeds to these machines. However, in these types of take-up and supply mechanisms, the yarn runs onto one end of a take-up drum from a supply package and is passed directly into the textile machine, such as a circular knitting machine, from the other end of the drum. An axial displacement of the yarn windings on the drum takes place along the surface of the drum and the mechanisms are continuously utilized during the supply of yarn from the supply packages to the textile machine and remain in the feeding path or zone of yarn flow during the entire machine operation.
Accordingly, these previously known yarn take-up and supply mechanisms could not be utilized for intermittently taking-up and supplying of a given length of yarn in a substantially tension-free condition to an associated textile machine and which would thereafter not be in the normal path of travel of the yarn through the textile machine during processing of the yarn therein.
Therefore, a need existed for a take-up and supply mechanism which could be intermittently used, for example at selective spindle assemblies of a textile yarn processing machine, for taking-up a given length of yarn and supplying this given length of yarn to the textile machine in a substantially tension-free condition for use in pneumatic or other threading of such textile machines. To fulfill this need, such a take-up and supply mechanism was proposed in applicant's U.S. Pat. No. 4,118,919, issued Oct. 10, 1978, and assigned to the assignee of the present application. Applicant's patent also discloses in the specification thereof U.S. patents setting forth the prior type of take-up and supply mechanisms, described above, which were typically utilized in weaving and knitting machines and which remained in the feeding path of the yarn flow during the entire machine operation and such prior art patents are incorporatd herein by reference along with German Patent Publication 1,063,537.
In applicant's U.S. Pat. No. 4,118.919, a yarn take-up and supply mechanism was provided which utilized a rotating drum mechanism for winding a given length of yarn on the outside surface thereof for subsequently supplying this wound length of yarn to the textile machine in a substantially tension-free condition. Although the yarn take-up and supply mechanism of applicant's prior U.S. Pat. No. 4,118,919 was a substantial improvement over prior yarn take-up and supply mechanisms and provided, for the first tme, a yarn take-up and supply mechanism which could be intermittently operated at a desired location, such as a particular spindle assembly, in a textile machine and which would not remain in the feeding path of yarn flow during the entire machine operation, this prior patented mechanism was necessarily complex in design and expensive to manufacture due to the use of the rotating drum.